Recently, many electric vehicles such as an electric vehicle that uses a motor as a driving source, a hybrid vehicle that uses a motor and an engine as a driving source, and the like, have been used. Such an electric vehicle includes a chargeable/dischargeable battery that supplies electric power to a motor and is charged by electric power generated by the motor when the motor is operating as a power generator. As a battery, a nickel-metal hydride battery, a lithium ion battery, or the like is used. As the temperature of such a battery increases when the battery is charged or discharged, a cooling device for cooling the battery is mounted on an electric vehicle.
A battery cooling device employs a method in which a temperature sensor is arranged at the inlet of a cooling channel of a battery, for adjusting the amount of air blown by a cooling fan, based on the temperature of a cooling air, detected by the temperature sensor, and the temperature of the battery detected by a battery temperature sensor, to cool the battery so as to be kept at a good operating temperature for the battery itself (for example, JP5355966). Note here that a battery device having two independent cooling systems for cooling a battery has been suggested. Further note that a cooling system includes a cooling fan and a cooling air duct (for example, JP2008-293853A).
In the case in which a plurality of independent cooling systems are included, as described in JP 2008-293853A, for example, it is often the case that the rotation speed of each cooling fan is controlled based on the temperature of cooling air detected by a temperature sensor arranged at the inlet of the relevant cooling channel of a battery and the temperature of a part of the battery cooled by the relevant cooling system. In this case, when such an abnormality that the resistance value of a thermistor is changed and accurate detection of the temperature is not possible should occur with the temperature characteristic of the temperature sensor, it is not possible to appropriately control the cooling fan of the cooling system with the temperature sensor subjected to abnormality. This makes it difficult to achieve appropriate control over the temperature of a part of the battery cooled by that cooling system.
In view of the above, abnormality determination as to temperature characteristic of a temperature sensor is important. However, in the case where a plurality of cooling systems are included, as the rotation speeds of the respective cooling fans are independently controlled, each based on the temperature detected by a temperature sensor provided to a cooling channel and the temperature of a part of a battery cooled by the cooling channel, a case may result in which the amounts of air blown by the respective cooling fans vary between the respective cooling systems, so that a difference is caused between the temperatures detected by the temperature sensors provided in the respective cooling channels. Moreover, as the respective positional relationships between a battery and respective temperature sensors are not constant, a case may result in which the temperature of the cooling air differs from between the inlets of the respective cooling channels due to influence of the temperature of the battery. This makes it difficult to make abnormality determination as to temperature characteristic of a temperature sensor, based on the difference between the temperatures detected by the temperature sensors provided to the respective cooling systems. In order to address the above, there is available a method in which two temperature sensors are arranged for each cooling system, for performing abnormality determination as to temperature characteristic of the temperature sensor, based on the difference between the temperatures detected by the two respective temperature sensors. This, however, causes a problem of an increased number of temperature sensors, and a resultantly complicated structure.
In view of the above, the present disclosure aims to achieve abnormality determination as to temperature characteristic of a temperature sensor, using a simple structure, in a battery device including a plurality of cooling systems.